1. Field of the Invention
This invention relates to electronic systems, and more particularly to portable modular electronic systems with symmetrical connections between modules.
2. Description of the Related Art
Numerous processor-controlled electronic applications (also referred to as “appliances”) have been developed, such as portable digital MP3 audio players, digital still or video cameras, digital voice recorders and personal data assistants (PDAs). Some of these applications must be plugged into a personal computer (PC) to operate, while others are stand-alone portable devices. For example, Moving Picture Experts Group Layer 3 Standard (MP3) players are portable with built-in hard drive memories. However, even such portable devices cannot interface with other applications without an intervening PC, and by themselves are limited to a single application.
Portable data storage devices are also available, e.g., a plug-and-play unit that is automatically detected as a removable drive when plugged into a USB (universal serial bus) port on a computer. It can be used to read, write, copy, delete and move data to or from a hard disk drive, and can play MP3 files, run applications or view videos. However, it has a limited storage capacity and, since it must be plugged into a computer, the overall system is not portable.
Some portable handheld computers have a connector at the bottom that enables consumers to snap-on various applications, such as a camera, Global Positioning System (GPS) receiver, bar code scanner, recorder or modem. However, the hand held computers are limited to only a single application at a time, and there is only one way to position an application device relative to the computer.
Controllers associated with a pair of redundant hard drives are also known, such as a RAID (redundant array of industry standard DIMMs (dual in-line memory modules)) system. Again, however, such systems are not portable. When used with a portable application such as an MP3 player, the application must be connected to the controller/memory combination and thus loses its portability.
It is important that any consumer-oriented electronic system be easy to assemble and operate. If the consumer is to be given options in configuring the system for different applications, it is highly desirable that the system have a degree of flexibility in its design so that it can tolerate variations in the way it is assembled by different, non-expert consumers.